Hypodermic syringe



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P 7 A. A. LAURENT HYPODERMIC SYRINGE Filed Aug. 21, 1926 Inventor.- f KLaurent.

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Patented Sept. 13, 1927.

ANTOINE A. LAURENE OF MINNEAPOLIS, MINNESOTA.

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Application filed August 21, 1926. Serial No. 130,761.

My invention relates to hypodermic syringes, and has for an object toprov de a syringe which can be held and operated with' great convenienceand which can be 5 maintained filled with a supply of liquid to beinjected hypodermically into the human body. This syringe is employed toin ect liquid into the human body for the production of what is knownaslocal anaesthesia, and may also be used for injecting serums andvaccines. It is essential for producing local anaesthesia to introducerelatively large quantities of the liquid into the area to beanaesthetized and it is therefore desirable that a syringe be providedwhich can be refilled or .kept 'in filled condition without havin toremove the hypodermic needle after has been inserted. This invention isin the nature of an improvement on Patent No. 1,367,008grantedFeb. l,1921, to A. N. Bessessen, and involves an improvement on thevalvec'onstruction'and arrangement disclosed in said patent. The fullobjects and advantages of my 1nvention will appear in connection-withthe detailed description thereof, and the "novel features of myinventive idea will beparticularly pointed out in the claims. In theaccompanying drawings which lllustrate a practical embodiment ofmyinvention,- I Y Fig. 1 is a view of the device partly in elevation andpartly in central-vertical section and showing the plun er moved in- 2is a view 0 the device-in central vertical section showing the plungermoved outwardly. Fig. 3 is a view in cross section on the line 3-3 ofFig. 2.

Referring to the drawings for the purpose 3 of describing the inventionin detail, the syringe comprises a cylindrical barrel 10 which at itsforward end is threaded toreceive a perforated cap 12. This cap is inturn threaded at its forward end to receive a hypodermic needle 14. Theinterior of the forward end of the barrel 10 is provided with a valveseat 16 with which a forwardly opening check valve 18 is adapted tocooperate, being normallyheld upon the valve seat by a spring 20. Thevalve 18 is in the form of a ball to which is secured a stem 22extending out through the passage in the cap 12 but smaller than thispassage so as not to prevent the flow of liquid therethrough. The rearend'of the barrel. 1() is'provided with a screw cap 24 havingtwo lateraldiametrically opposed curved finger grips Slidable' in thebarrel 10 is ahollow plunger 28 having a head 30 at the lower end thereof, and atransverse partition 32 intermediate the upper and lower ends. The uppersurface of the head SO'is provided centrally with a rounded recess 34from which perforations 36 extend to the lower surface of the head.These perforationsare located outside of the axialline of the plunger.The lower sideof the partition 32 is provided centrally with a roundedrecess 38. The recesses 84 and 38 constitute seats for a ball valve 40having a limited movement between the two seats. A rod 42 extendsupwardly from the ball 40, this rod being hollow to provide a passage 44which is extended cen-' trally through the ball. The rod 42 in effectconstitutes a plunger rod. Tightly secured upon the rod42 is a sleeve 46which except for convenience in manufacture might be made integralwiththe rod. The sleeve 46 passes snugly through a central opening in thecap 24 and at its upper end is threaded to receive an internallythreaded boss 48 formed on a-handpiece 5O shaped to receive the palmofthe hand. The hand piece 50 contains a passage 52 which communicateswiththe passage 44 and extends through a nipple 54 to which is attachedapiece of rubber tubing 56, adapted to be connected with the source ofsupply of liquid. The lower end of the sleeve 46 has a flange 58 towhich is anchored a coiled spring 60 whose upper end is anchored to aring 62 held between the cap 24 and the upper end of the barrel 10. I

In use, the hypodermic needle may be readily inserted where desired inthe human body and with the fingers around the finger 9 grips 26 and thepalm of the hand upon the hand piece 50, pressure is exerted upon theplunger to cause the liquid below the latter to be forced through theneedle into the part to'be anaesthetized or into whichrserum or vaccineis to be injected. At the same time, the spring 60 is stretched and theball valve moves from theupper seat 38 into engagement with the lowerseat 34; Upon releasing the pressure of the hand, the spring retractsthe plunger thereby producing a vacuum in vthe barrel below the plungerand causing liquid to flow from the source of supply into the vacuumchamber, the ball 40 then being in the position shown in Fig. 2 so thatthere is a free passage through the ball 40 and the perforations 36.Upon starting to depress the plunger. the hall 40 first moves intoposition upon the seat 34 as shown that back-How of the liquid isprevented. lVhile the ball has a limited amount of movement between thetwo seats, the construction in effect constitutes a ball and socketconnection between the plunger and its rod so that there is no liabilityof the plunger being subjected to side thrust which might cause it tobind. The ball. therefore, has a three-fold function since it acts as acheck valve when in the position shown in Fig. l and allows the liquidto pass directly therethrough when in the position shown in Fig. Thereis a special utility for the stem 22 attached to the check valve 18 dueto the fact that there is liability of this valve becoming stuck to itsseat after the device has been used. hen such sticking occurs, the valveis readily released by pushing sidewise on the projecting end of thestern when the needle is detached.

I claim:

1. In a hypodermic syringe having a barrel provided with an outletopening containing an outwardly opening check valve, the combination ofa plunger working in said barrel, a plunger rod, a ball on the inner endof said rod for connecting the latter with said plunger and having alimited movement with relation thereto, said rod and ball togetherhaving a passage for liquid, a perforated head for said plunger withwhich said ball engages when in forward position for preventing backwardHow of liquid through said passage, and means for conin Fig. 1 sonecting the outer end of said rod with a source of lhpiid supply.

2. In a iypodermic syringe having a barrel provided with an outletopening con taining an outwardly opening check valve, the combination ofa plunger working in said barrel, a plunger rod, a perforated head and atransverse partition for said plunger, said head and partition havingrounded recesses facing each other, a ball on the inner end of saidplunger rod having a limited movement between said recesses, said balland rod together having a passage for liquid, said hall when in forwardposition engaging the recess in said head for preventing backward flowof liquid through said passage, and means for connecting the outer endof said rod with a ply.

3. In a hypodermic syringe having a barrel provided with an outletopening containing an outwardly opening check valve. the combination ofa plunger working in said barrel, a spring for normally holding saidplunger in retracted position, a plunger rod, a ball on the inner endoi'said rod for connecting the latter with said plunger and having alimited movement with relation thereto, said ball and rod togetherhaving a passage for liquid, means for preventing backward flow ofliquid through said passage, and means for connecting the outer end ofsaid rod with a source of liquid supply.

In testimony whereof I hereunto aflix my signature.

ANTOINE A. LAURENT.

source of liquid sup-

